A month ago, Apple noted that it has 1.8 million developers in China (and/or developers publishing to China -- not clear to me). At any rate, the Apple platform has made those developers $17 billion dollars.[1]
So China is big business for Apple developers and I assume many of those developers are US/CA/EU/AU/etc. who benefit from the platform being available in China.
[1] https://www.cnbc.com/2017/12/03/apples-tim-cook-says-develop...